Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the most common sequelae of severe sepsis leading to greater than 40% mortality. In the 200,000 people fortunate enough to survive ALI annually, many years of persisting pulmonary disability, cognitive abnormalities, and post-traumatic stress disorder result. Proinflammatory and procoagulant processes uniformly follow the onset of sepsis. They damage lung vasculature and alveolar epithelium and lead to ALI/ARDS. Three decades of efforts to attenuate septic responses that induce lung injury using targeted single mediator antagonism have failed to reduce mortality. Only low tidal volume lung-protective ventilation and conservative fluid management strategies show a mortality benefit. An intervention that attenuates multiple, dysregulated pathways seems most likely to improve outcomes. This application presents new data showing that parenterally infused high dose ascorbic acid (vitamin C) disrupts multiple proinflammatory/procoagulant cascades that lead to lung injury in septic humans and mice. Subnormal plasma vitamin C levels are a consistent feature in septic patients, varying inversely with the incidence of multiple organ failure and directly with survival No multicenter trials have examined parenteral vitamin C infusion as an intervention to attenuate sepsis-induced lung injury. We propose to conduct a randomized, double-blind, placebo-controlled, multi-center phase II proof of concept trial examining high dose intravenous vitamin C (ascorbic acid) infusion in human sepsis induced acute lung injury. Our central hypothesis is that: Parenteral augmentation of vitamin C (ascorbic acid) by intravenous infusion will attenuate lung injury that follows onset of severe sepsis. We further hypothesize that: Attenuated lung injury in patients receiving vitamin C will be associated with reduced plasma levels of injury biomarkers and improved measurements of lung function. The proposal contains a tightly linked basic science lung injury study in a murine model of septic lung injury employing mice in whom enzyme that synthesizes vitamin C has been knocked out, thus simulating human sepsis. The phase 11 trial will be conducted by 4 highly experienced physician- investigators with a history of lung injury research.